Working toward the goal of developing increased understanding of the motivational structure underlying childbearing and family size desires and expectations, this study focuses upon (a) social role theory, examining particularly the role expectations of both sexes as developed through the process of socialization, the degree of flexibility in role limits, and alternative ways of fulfilling role requirements, (b) the personality dimension of inner vs. outer control over the effects of one's behavior, and (c) the level of understanding of the relationship of population growth to current environmental problems, in order to develop a model of the interacting components, and from this to devise a survey instrument to assess these dimensions in two age groups, pre-childbearing (11-16 years) and typical childbearing (19-24 years), stratified according to sex, race, religion, educational level or aspired level, and population density of place of residence. On the basis of findings from the survey instrument, the second stage would consist of the development and testing of prototypic educational programs designed to complement the underlying motivational structure and hypothesized to affect desires and decisions regarding childbearing and family size. Two experimental plans for testing these educational programs in different settings are suggested in order to evaluate their interaction with manifest desires and expectations and with childbearing behavior.